Norikazu Ohno

Ti Nano-nodular Structuring for Bone Integration and Regeneration

Nanostructuring technology has been proven to create unique biological properties in various biomaterials. Here we present a discovered phenomenon of titanium nano-nodular self-assembly that occurs during physical vapor depositions of titanium (Ti) onto specifically conditioned micro-textured titanium surfaces, and test a hypothesis that the Ti nanostructure has the potential to enhance bone-titanium integration. The nanostructure creation effectively provided geometrical undercut and increased the surface area by up to 40% compared with the acid-etched surface with microtopography. Depending on the size control, the nano-nodules can be added without smearing the existing micro-texture, creating a nano-micro-hybrid architecture. Titanium implants with 560-nm nano-nodules produced 3.1 times greater strength of osseointegration than those with an acid-etched surface in a rat femur model. The discovered titanium nano-nodular self-structuring has been proven feasible on biocompatible materials other than titanium, offering new avenues for the development of implant surfaces and other implantable materials for better bone-generative and -regenerative potential.

Distribution of fluoride concentration in the rat's bone.

SummaryThe present study was undertaken to determine the fluoride distribution profile in the rat femur. Male Wistar rats were divided into four groups and given water containing 0, 25, 50, and 100 ppm of fluoride, respectively, for 10 weeks. The fluoride distribution from the periosteum to the endosteum was determined in each specimen after sampling using the abrasive microsampling technique [5]. In the outer circumferential lamellae, the concentration of fluoride was relatively high in the periosteal layer and then decreased gradually towards its interior. In the haversian and interstitial lamelae, it was lower and roughly constant through the tissue. In the inner circumferential lamellae, it rose again to reach the highest level towards the endosteal surface. Fluoride concentration throughout the cortex increased significantly with increasing intake of fluoride. These increases were especially marked at periosteal and endosteal surfaces.

Anatomical study of the root apex in the maxillary anterior teeth

This study was undertaken to anatomically investigate the apical portion of root canal. Teeth used in this study were thirty maxillary central incisors, thirty maxillary lateral incisors and thirty maxillary cuspids extracted from patients between the ages of 11 and 73. All of the teeth had periodontal disease, but none had periapical disease. Resorption of the root surface could not be seen with the naked eye. The results obtained were as follows: 1. Deviations of the root apex and the apical foramen. Both of the root apex and apical foramen of the central incisors and cuspids were displaced distolabially from the tooth axis. Those of the lateral incisors were displaced distolingually from the tooth axis. The coincidence between the root apex and apical foramen was found in 16.7 per cent of both the central incisors and the cuspids, and in 6.7 per cent of the lateral incisors. 2. Diameters of the apical foramen and perpendicular distances between the root apex and apical foramen. The labiolingual diameters in the apical foramen of the central incisors, the lateral incisors and the cuspids were 0.504 mm, 0.452 mm and 0.425 mm respectively. Those diameters were larger than the mesiodistal diameters in the maxillary anterior teeth. Both the labiolingual and mesiodistal diameters in the central incisors were the largest. The perpendicular distances between the root apex and the apical foramen of the central incisors, lateral incisors and cuspids were 0.450 mm, 0.440 mm and 0.510 mm respectively. Those in the cuspids were the largest. The apical foramen in the cuspids was located slightly closer to the cervical side. 3. Diameters of the apical constriction and perpendicular distances between the root apex and apical constriction. The apical constriction of the root canal was located in either cementum or dentin. The labiolingual diameters of the root canal in the apical constriction of the central incisors, the lateral incisors and the cuspids were 0.425 mm, 0.369 mm and 0.425 mm respectively. The root canal labiolingual diameters in the maxillary anterior teeth was approximately 0.050 mm larger than mesiodistal diameters. The shapes of the root canal in the apical constriction were mostly the circular, oval and ovoid, while a few irregular shapes were observed. The perpendicular distances between the root apex and the apical constriction of the root canal in the central incisors, the lateral incisors and the cuspids were 0.863 mm, 0.825 mm and 1.010 mm respectively. 4. The stricture ratio of diameter between the apical foramen and the apical constriction of the root canal.(ABSTRACT TRUNCATED AT 400 WORDS)

Anchoring and length regulation of Porphyromonas gingivalis Mfa1 fimbriae by the downstream gene product Mfa2.

Porphyromonas gingivalis, a causative agent of periodontitis, has at least two types of thin, single-stranded fimbriae, termed FimA and Mfa1 (according to the names of major subunits), which can be discriminated by filament length and by the size of their major fimbrilin subunits. FimA fimbriae are long filaments that are easily detached from cells, whereas Mfa1 fimbriae are short filaments that are tightly bound to cells. However, a P. gingivalis ATCC 33277-derived mutant deficient in mfa2, a gene downstream of mfa1, produced long filaments (10 times longer than those of the parent), easily detached from the cell surface, similar to FimA fimbriae. Longer Mfa1 fimbriae contributed to stronger autoaggregation of bacterial cells. Complementation of the mutant with the wild-type mfa2 allele in trans restored the parental phenotype. Mfa2 is present in the outer membrane of P. gingivalis, but does not co-purify with the Mfa1 fimbriae. However, co-immunoprecipitation demonstrated that Mfa2 and Mfa1 are associated with each other in whole P. gingivalis cells. Furthermore, immunogold microscopy, including double labelling, confirmed that Mfa2 was located on the cell surface and likely associated with Mfa1 fimbriae. Mfa2 may therefore play a role as an anchor for the Mfa1 fimbriae and also as a regulator of Mfa1 filament length. Two additional downstream genes (pgn0289 and pgn0290) are co-transcribed with mfa1 (pgn0287) and mfa2 (pgn0288), and proteins derived from pgn0289, pgn0290 and pgn0291 appear to be accessory fimbrial components.

Asian domains of four major genotypes of JC virus, Af2, B1-b, CY and SC.

Summary. JC virus (JCV) strains worldwide can be classified into various genotypes based on DNA sequence variations. To define the domains of the four major JCV genotypes in Asia, we collected urine samples at six unstudied sites: three in southeastern Asia, two in the central highlands and one in central Asia. DNA was extracted from urine samples, and used to amplify a 610-bp region of the viral genome. For each geographical site, we determined 16 to 31 sequences, from which a phylogenetic tree was constructed to unambiguously classify detected JCV isolates into distinct genotypes. From JCV genotype profiles at the sites studied here and elsewhere, the following conclusions were drawn. Although Af2 is the major genotype in Africa, this genotype also occurs in western and central Asia. B1-b mainly occurs in western and central Asia, including the central highlands. CY occurs in northeastern Asia with the southern boundary between China and southeast Asian countries. Although SC predominates in southeastern Asia, it also occurs in northern and central Asia at lower frequencies. In addition, a few minor JCV genotypes (B1-a, B2 and B3) occur at many sites. We discuss here the anthropological and medical significance of the present findings.

Localization of Major, High Molecular Weight Proteins in Bacteroides forsythus

Bacteroides forsythus produces species‐specific major proteins with high molecular weights of 270 and 230‐kDa (270K and 230K). A specific antibody raised against 270K was used for Western blot analysis and immunoelectron microscopy. Western blot analysis showed that the 270K and 230K proteins were immunologically similar. Immunogold labeling of ultrathin‐sectioned bacterial cells and biochemical fractionation revealed that these proteins were localized at the outermost cell surface, not in the cytoplasm. These results suggest that major proteins ubiquitous to this species may form the S‐layer.

Aetiology, incidence and morphology of the C-shaped root canal system and its impact on clinical endodontics

The C-shaped root canal constitutes an unusual root morphology that can be found primarily in mandibular second permanent molars. Due to the complexity of their structure, C-shaped root canal systems may complicate endodontic interventions. A thorough understanding of root canal morphology is therefore imperative for proper diagnosis and successful treatment. This review aims to summarize current knowledge regarding C-shaped roots and root canals, from basic morphology to advanced endodontic procedures. To this end, a systematic search was conducted using the MEDLINE, BIOSIS, Cochrane Library, EMBASE, Google Scholar, Web of Science, PLoS and BioMed Central databases, and many rarely cited articles were included. Furthermore, four interactive 3D models of extracted teeth are introduced that will allow for a better understanding of the complex C-shaped root canal morphology. In addition, the present publication includes an embedded best-practice video showing an exemplary root canal procedure on a tooth with a pronounced C-shaped root canal. The survey of this unusual structure concludes with a number of suggestions concerning future research efforts.

Fluoride distribution and histological structure of human cementum

Thirty-one teeth taken post-mortem from 10 subjects aged from 40 to 66 years were studied. A close relationship was found between fluoride (F) distribution and histological structure. Although, as in all mineralized tissues, F concentrations tended to be highest towards the external surface, individual patterns of F distribution also seemed to reflect the histological pattern, especially the distribution of cellular or acellular cementum. In general, F concentrations were high in acellular and low in cellular cementum.

Periodontitis-activated monocytes/macrophages cause aortic inflammation

A relationship between periodontal disease and atherosclerosis has been suggested by epidemiological studies. Ligature-induced experimental periodontitis is an adequate model for clinical periodontitis, which starts from plaque accumulation, followed by inflammation in the periodontal tissue. Here we have demonstrated using a ligature-induced periodontitis model that periodontitis activates monocytes/macrophages, which subsequently circulate in the blood and adhere to vascular endothelial cells without altering the serum TNF-α concentration. Adherent monocytes/macrophages induced NF-κB activation and VCAM-1 expression in the endothelium and increased the expression of the TNF-α signaling cascade in the aorta. Peripheral blood-derived mononuclear cells from rats with experimental periodontitis showed enhanced adhesion and increased NF-κB/VCAM-1 in cultured vascular endothelial cells. Our results suggest that periodontitis triggers the initial pathogenesis of atherosclerosis, inflammation of the vasculature, through activating monocytes/macrophages.

Increased Expression of Interleukin (IL)-35 and IL-17, But Not IL-27, in Gingival Tissues With Chronic Periodontitis

BACKGROUND Interleukin (IL)-35 plays an important role in immune regulation through the suppression of effector T-cell populations, including T-helper 17 (Th17) cells. Although Th17 cells and IL-17 are involved in the pathogenesis of periodontitis, the level of IL-35 in inflamed periodontal tissues is unclear. Here, IL-35, IL-17, and IL-27 production/expression in gingival crevicular fluid (GCF) and human gingival tissue were investigated. METHODS GCF samples were collected from buccal (mesial, center, and distal) sites of teeth from patients with chronic periodontitis (CP) and healthy controls and were analyzed by enzyme-linked immunosorbent assay for IL-35 (periodontitis, n = 36; healthy, n = 30) and IL-17 (periodontitis, n = 16; healthy, n = 13). Gingival tissue, including sulcus/pocket epithelium and underlying connective tissue, was collected from an additional 10 healthy participants and 10 patients with CP and were analyzed by quantitative polymerase chain reaction (qPCR) for Epstein Barr virus-induced gene 3 (EBI3), IL12A, and IL17A. IL27p28 was also tested by qPCR. RESULTS IL-35 and IL-17 were significantly higher in GCF from patients with periodontitis than healthy participants (P <0.01, P <0.05, respectively). In both healthy participants and those with periodontitis, positive correlations were found among IL-35 and probing depth and clinical attachment level (CAL) as well as between IL-17 and CAL. EBI3, IL12A (components of IL-35), and IL17A messenger RNA expression levels were significantly higher in inflamed gingival tissue than in healthy control tissues (P <0.05). IL27p28 was not detected in any sample, suggesting that IL-27 is not produced in large quantities in periodontal tissue. CONCLUSION IL-35 and IL-17, but not IL-27, may play important roles in the pathogenesis of periodontitis.